Halide (or hydride) vapor phase epitaxy (HVPE) of GaN and of other Group III-V compounds has known problems that result in an inefficient conversion of the precursor gases to GaN at the substrate. One problem relates to the temperature of precursor gases. In the case of GaN, if the entry temperature of the GaCl3 and NH3 is less than about 850° C., undesirable GaCl3:NH3 complexes may form that can limit the desired direct reaction between GaCl3 and NH3 to form GaN. A further problem arises if the precursor gases mix prematurely prior to their coming into contact in the immediate vicinity of the substrate. Premature mixing of the precursor gases can result in unwanted gas phase reaction by-products and the production of particulates within the reactor, both of which can lead to a decrease in product quality.
A further problem arises from undesired deposition on the interior walls of a growth chamber. In the case of GaN, the undesirable deposition occurs since the Ga containing precursors, e.g., GaCl or GaCl3, condense from the vapor phase at relatively low temperatures (generally less than 500° C.) and, therefore, areas of the reactor that are not maintained at a temperature above the vaporization zone can become coated. Over time, this unwanted material can build up to the extent of resulting in inefficient heating of the chamber as well as to production of quality-decreasing particulates.
Therefore, the prior art of Group III-V compound growth can benefit from apparatus that improve the thermalization and the delivery of precursor gases into a growth chamber. Such improvements will result in a more efficient utilization of precursor gases with associated cost reduction. However, such apparatus has not been available, at least because the physical space in growth chambers suitable for commercial production is very limited and the addition of further apparatus can compromise the effectiveness of mechanical substrate transfer systems or can be limited by available clearances for, e.g., inlet and exhaust lines.